State agreement

Mr Burke wants the agreement of the affected states - Queensland, New South Wales, Victoria and South Australia - before signing off on the final Murray-Darling Basin Plan.

The Prime Minister's announcement has won the immediate backing of South Australian Premier Jay Weatherill, who says he will drop proposed High Court action against the basin plan if the new measures are adopted.

"I asked all South Australians to stand up and make their voices heard and they have; irrigators, environmentalists, city and country folk have answered that call getting involved in the campaign," he said.

A simple demand was to listen to the scientists to return more water and the Federal Government have now done that, so this is a very big day for SA.

SA Premier Jay Weatherill

"A simple demand was to listen to the scientists to return more water and the Federal Government have now done that, so this is a very big day for South Australia."

New South Wales and Victoria have been campaigning for a limit of 2,100 gigalitres on how much water can be recovered for environmental flows.

Victoria Water Minister Peter Walsh has told the ABC's Country Hour that his Government's position has not changed.

"We will not be supporting a 3,200 gigalitre plan," Mr Walsh said.

"We do not yet have a resolution to a 2,750 gigalitre plan, we don't have the level of confidence with the methodology around the sustainable diversion offsets yet.

"My view is the Commonwealth would be far better off working with the states to resolve the issues that are currently on the table, rather than rushing over to South Australia for a stunt just to appease the South Australian Premier."

The NSW Government says it is disappointed the Prime Minister has chosen to "throw money" at an increased target before getting agreement on the original plan.

"The Federal Government has provided funding for an increased target of 3,200 gigalitres but failed to adequately address our concerns in reaching their original target of 2,750 gigalitres," the state's Deputy Premier Andrew Stoner said in a statement.

"Questions remain about a practical and sensible approach to reaching the initial sustainable diversion limit (SDL) target of 2750GL in a manner that does not jeopardise our basin communities."

Timing

The Murray-Darling Basin Plan is due to be finalised by the end of the year.

The Coalition has welcomed the extra investment in on-farm infrastructure, but has questioned the 2024 timeframe for delivering the funding.

"They'll be lucky to be there next year, let along 2024," Nationals Senator Barnaby Joyce said.

"So, what does this statement actually mean?

"It's a wonderful aspiration, and I suppose it makes the South Australians happy - and good luck to them.

"How can you back a wish? You only back something if they've got the money put aside for it, otherwise it is a nothing statement."

How can you back a wish? You only back something if they've got the money put aside for it, otherwise it is a nothing statement.

Nationals Senator Barnaby Joyce

His South Australian colleague, Liberal Senator Simon Birmingham, wants to see more details before passing final judgement.

"As always, the devil will be in the detail and in the timing of delivery of this and where the money is coming from," he said.

"South Australians have had many false dawns before and on this occasion we want to make sure that we actually get the right outcomes for the river."

Conservationists are pushing for further increases to the 3,200 gigalitre target, while irrigators have questioned how the on-farm infrastructure funding will work.

The Australian Conservation Foundation's Dr Paul Sinclair says returning 3,200 gigalitres of water to the river system is a good start, but he would like to see the quantity increased during the next decade.

"[It's] a substantial improvement on the 2,750 [gigalitres] that Governments have been shopping around," he said.

"What's also clear is that it's possible over time on the best available science to move that target upwards so that we can achieve 85 per cent of the targets the Murray-Darling Basin Authority have set for a healthy river system."